Intangible Assets (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 155,735,000	$ 145,854,000
Accumulated Amortization	94,556,000	81,906,000
Total	61,179,000	63,948,000
Amortization expense	12,600,000	13,400,000	12,400,000
Estimated future amortization expense [Abstract]
2013	12,515,000
2014	11,087,000
2015	6,557,000
2016	4,785,000
2017	3,129,000
2018 and thereafter	23,106,000
Total	61,179,000	63,948,000
Intangible assets not subject to amortization	29,000,000	29,000,000
Indefinite-lived intangible asset impairment loss		900,000
Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	1 year
Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	25 years
Customer Contracts [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	59,305,000	59,240,000
Accumulated Amortization	44,571,000	37,763,000
Total	14,734,000	21,477,000
Estimated future amortization expense [Abstract]
Total	14,734,000	21,477,000
Acquired Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	29,287,000	26,757,000
Accumulated Amortization	24,299,000	23,129,000
Total	4,988,000	3,628,000
Estimated future amortization expense [Abstract]
Total	4,988,000	3,628,000
Patents [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	24,337,000	24,125,000
Accumulated Amortization	12,723,000	10,205,000
Total	11,614,000	13,920,000
Estimated future amortization expense [Abstract]
Total	11,614,000	13,920,000
Distributor and Provider Networks [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	8,709,000	8,709,000
Accumulated Amortization	6,669,000	6,148,000
Total	2,040,000	2,561,000
Estimated future amortization expense [Abstract]
Total	2,040,000	2,561,000
Perpetual License to Survey-Based Data [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	29,000,000	21,956,000
Accumulated Amortization	2,708,000	1,607,000
Total	26,292,000	20,349,000
Estimated future amortization expense [Abstract]
Total	26,292,000	20,349,000
Other [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	5,097,000	5,067,000
Accumulated Amortization	3,586,000	3,054,000
Total	1,511,000	2,013,000
Estimated future amortization expense [Abstract]
Total	$ 1,511,000	$ 2,013,000